School of Life Sciences, Wellesbourne Campus, University of Warwick, Wellesbourne, Warwickshire CV35 9EF, United Kingdom.
Chemosphere. 2012 Jun;88(1):77-83. doi: 10.1016/j.chemosphere.2012.02.066. Epub 2012 Mar 31.
There is considerable current interest in using biochar (BC) as a soil amendment to sequester carbon to mitigate climate change. However, the implications of adding BC to agricultural soil for the environmental fate of pesticides remain unclear. In particular, the effect of biochars on desorption behavior of compounds is poorly understood. This study examined the influence of BC on pesticide chemical and biological accessibility using the herbicide isoproturon (IPU). Soils amended with 1% and 2% BC showed enhanced sorption, slower desorption, and reduced biodegradation of IPU. Addition of 0.1% BC had no effect on sorption, desorption or biodegradation of IPU. However, the mineralization of (14)C-IPU was reduced by all BC concentrations, reducing by 13.6%, 40.1% and 49.8% at BC concentrations of 0.1%, 1% and 2% respectively. Further, the ratio of the toxic metabolite 4-isopropyl-aniline to intact IPU was substantially reduced by higher BC concentrations. Hydroxypropyl-β-cyclodextrin (HPCD) extractions were used to estimate the IPU bioaccessibility in the BC-amended soil. Significant correlations were found between HPCD-extracted (14)C-IPU and the IPU desorbed (%) (r(2)=0.8518, p<0.01), and also the (14)C-IPU mineralized (%) (r(2)=0.733; p<0.01) for all BC-amended soils. This study clearly demonstrates how desorption in the presence of BC is intimately related to pesticide biodegradation by the indigenous soil microbiota. BC application to agricultural soils can affect the persistence of pesticides as well as the fate of their degradation products. This has important implications for the effectiveness of pesticides as well as the sequestration of contaminants in soils.
目前，人们对使用生物炭（BC）作为土壤改良剂来固定碳以减缓气候变化非常感兴趣。然而，向农业土壤中添加 BC 对农药的环境归宿的影响仍不清楚。特别是，生物炭对化合物解吸行为的影响还不太了解。本研究使用除草剂异丙隆（IPU）研究了 BC 对农药化学和生物可利用性的影响。添加 1%和 2%的 BC 的土壤表现出增强的吸附、较慢的解吸和降低的 IPU 生物降解。添加 0.1%的 BC 对 IPU 的吸附、解吸或生物降解没有影响。然而，所有 BC 浓度均降低了 (14)C-IPU 的矿化，在 BC 浓度为 0.1%、1%和 2%时，分别降低了 13.6%、40.1%和 49.8%。此外，较高的 BC 浓度大大降低了有毒代谢物 4-异丙基苯胺与完整 IPU 的比例。使用羟丙基-β-环糊精（HPCD）提取来估计 BC 改性土壤中 IPU 的生物可利用性。在所有添加 BC 的土壤中，均发现 HPCD 提取的 (14)C-IPU 与 IPU 解吸（%）（r(2)=0.8518，p<0.01）之间存在显著相关性，与 (14)C-IPU 矿化（%）（r(2)=0.733；p<0.01）之间也存在显著相关性。本研究清楚地表明了在 BC 存在的情况下解吸与土著土壤微生物区系对农药的生物降解有多么密切的关系。将 BC 应用于农业土壤会影响农药的持久性及其降解产物的归宿。这对农药的有效性以及污染物在土壤中的固定都有重要意义。
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